This invention relates to strain relief devices, and particularly to an elastomeric, molded strain relief shaped to simplify insertion into an opening in a housing of electrical equipment and to prevent the strain relief and the electric cord onto which it is molded from being easily withdrawn from the housing.
The use of strain relief devices to prevent electrical cords from being easily pulled out of electrical equipment is well known. Some strain relief devices have metal parts that are mechanically deformed, for example, by crimping them, to hold them firmly around an electrical cord. Other such devices are made of rigid plastic, shaped so as to grip the cord firmly when in place in an opening in the wall of a housing of electrical equipment.
It is also known to mold an enlarged elastomeric member at a specific place on an electric cord, the molded member being provided with flanges or shoulders or projections to engage the wall of the electrical device for which the electric cord serves as a means of connection to a wall socket. A device of the latter type is shown in U.S. Pat. No. 2,712,119. In order to hold it in place, it is inserted in a first plate that is attached to the wall on the unit, such as a vacuum cleaner, with which it is to be used. The wall of the unit has an additional opening with an edge so arranged as to fit into a slot in the elastomeric strain relief member when the latter, and the plate to which it is initially attached, are slid into place covering the opening in the wall of the electrical unit. The shape of the elastomeric strain relief member is such that it cannot be inserted into operative position after the remainder of the housing has been assembled, which is disadvantageous in many instances.